Safety switch



June 2, 1970 W,P.HE.;.SQN ETAL 3,515,824

SAFETY SWITCH Filed June 20, 1968 Fig. 1

WILLIAM P. HENSON ROSS S. WOODS 2 INVENTORS wwiailm ww%w ATTORNEYS United States Patent 3,515,824 SAFETY SWITCH William P. Henson, Indianapolis, and Ross S. Woods, Greenfield, Ind., assignors to Mobile Drilling Company, Inc., Indianapolis, Ind., a corporation of Indiana Filed June 20, 1968, Ser. No. 738,614 Int. Cl. Hlllh 3/14 US. Cl. 200-52 3 Claims ABSTRACT OF THE DISCLOSURE A safety switch for shutting off machinery and including a tensioned electrical conductor extending through a ring shaped electrical conductor and movable against the ring shaped electrical conductor to make a circuit and shut off the machinery.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a safety switch.

Description of the prior art Various safety devices are provided in the prior art for shutting down machinery or for preventing a machine operator from being injured by machinery. For example, some machines are provided with a large red button which may have additional appropriate informational markings whereby the machine operator can quickly shut down the machine. In certain situations, however, the operator cannot reach the red button because he has been drawn into the machinery or is on the other side of the machine. Certain other types of safety devices as well as the red button require the operator or an object to be forced against the safety device in only one direction or else the safety device will not operate to shut down the machine. Certain other prior art safety devices are not as sturdy as might be desired.

SUMMARY OF THE INVENTION One embodiment of this invention might include a flexible wire mounted on machinery so as to extend across the machinery between the operator and the machinery, said flexible wire being operatively associated with an electrical circuit arranged to shut olf said machinery, said flexible wire being responsive to movement thereof to operate said electrical circuit to shut off said machinery.

A primary object of this invention is to provide an improved safety device.

Another object of the invention is to provide a safety switch which is more sturdy than conventional safety switches.

Still another object of the invention is to provide a safety device operable by a movement in any direction.

Still a further object of the invention is to provide a safety device which protects a substantial area around a machine.

Related objects and advantages will become apparent as the description proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS The full nature of the invention will be understood from the accompanying drawings and the following description of the claims.

FIG. 1 is a perspective view of the rear of the truck having a drill rig mounted thereon and incorporating the safety device of the present invention.

FIG. 2 is a schematic view of the electrical circuit of the safety device of the present invention.

3,515,824 Patented June 2, 1970 DESCRIPTION OF THE PREFERRED EMBODIMENT For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring now more particularly to the drawings, there is illustrated a truck 10 having a drill rig 11 mounted on the bed of the truck. Extending completely across the rear of the truck is a cable 12 which is mounted on the rear of the truck by means of two projections 15 and 16 extending rearwardly from the frame 17 of the truck.

At the center of the rear of the frame 17 of the truck there is mounted an eyelet 20 which is also an electrical conductor and has the electrically conductive cable 12 extending through the center of the eyelet 20. It will be noted that the eyelet 20 has a circular, tore or ring shaped configuration. Also the eyelet 20 is mounted within an insulating block 21 (FIG. 2) which insulates the eyelet from the frame 17 of the truck.

The cable 12 is fixed to the projection 15 and is electrically connected to the projection 15 which is also an electrical conductor and is mounted to the frame 17 of the truck so that cable 12 is grounded. The projection 16 has a spring 22 fixed thereto with the other end 25 of the spring being connected to the cable 12 and holding the cable 12 in tension. The parts are so proportioned and arranged that the normal tensioned position of the cable 12 is at the axis of the ring or tore 20.

Referring now more particularly to FIG. 2, the electrical circuit of the present invention is illustrated as including the grounded electrically conductive cable 12, the electrically conductive ring 20 and a line 26 which extends between the ring 20 and a conventional latching relay 27. The latching relay 27 may be, for example, a relay manufactured by Line Electric Company model No. RLPID- twelve volt DC. The circuit further includes a battery 30 which has one of its terminals 31 grounded at 32 to the frame 17 and which has its other terminal 35 connected to one side of an ignition switch 36 which may, for example, be located at the drill rig control panel (not shown). The other side of the switch 36 is connected by means of the line 37 to the latching relay 27. Also connected to the latching relay 27 is a further line 38 which leads from the ignition switch and branches into two portions 39 and 43 for connection to the latching relay 27. Still another output terminal 40 of the latching relay 27 is connected to ground at 41.

The output terminal 42 of the latching relay is connected by means of a line 45 to an indicator light 46 the other terminal 47 of which is connected to ground at 50. The output terminal 42 of the latching relay 27 is also connected to an ignition coil 50 of the machinery (drill rig) engine through the line 51, the other side of the ignition coil 50 being connected through line 52 to the distributor of the engine for the drill rig. It should be understood that various electrical circuits could be used with the present invention but that the present electrical circuit is intended to provide an arrangement whereby the contacting of the cable 12 to the electrical conductor 20 causes the engine to be shut off and presents restarting of the engine by means of the latching relay 27 until the ignition switch 36 is again operated. Since the details of internal construction of the latching relay 27 are conventional, the relay will not be further described.

It will be evident from the above description that the present invention provides an improved safety device. It will also be evident that the present invention provides a safety switch which is more sturdy than conventional safety switches and which is operable by movement of the cable 12 in any direction. It can also be appreciated that the cable 12 covers a substantial area of the truck (the entire rear of the bed) and in fact covers the entire area adjacent to which the operator will be located or working so that substantial protection is provided to the operator.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are also desired to be protected.

The invention claimed is:

-1. A safety device for use with machinery comprising a flexible wire electrical conductor secured at one end to said machinery, a further electrical conductor having a closed configuration, an electrical circuit arranged to control said machinery, said further electrical conductor being mounted on said machinery and electrically connected to said electrical circuit, said flexible wire also being electrically connected to said electrical circuit, said further electrical conductor being arranged so that its closed configuration surrounds said flexible wire, said flexible wire having its other end secured to said machinery, said wire having suflicient tension therein to prevent it from operating said electrical circuit but also being yieldably movable into electrical contact with said closed configuration of said further electrical conductor to operate said electrical circuit to control said machinery.

2. A safety device for use with machinery comprising a flexible wire electrical conductor secured at one end to said machinery, a further electrical conductor having a closed configuration, an electrical circuit arranged to control said machinery, said further electrical conductor being mounted on said machinery and electrically connected to said electrical circuit, said flexible wire also being electrically connected to said electrical circuit, said further electrical conductor being arranged so that its closed configuration surrounds said flexible wire, said flexible wire being movable into electrical contact with said closed configuration of said further electrical conductor to operate said electrical circuit to control said machinery, and spring means connected between the other end of said flexible wire and said machinery and providing tension in said flexible wire to prevent it from operating said electrical circuit.

3. The safety device of claim 2 wherein said flexible wire is mounted so as to extend across a portion of the machinery where an operator might be located so that the flexible wire is moved if the operator falls against the machinery.

References Cited UNITED STATES PATENTS 2,075,147 3/1937 Stotts ZOO-61.93 2,554,371 5/1951 Marx 20061.44 2,813,940 11/1957 Poet 20O-61.44 2,919,318 12/1959 Brown ZOO-61.93 X 3,226,518 12/1965 Kobus.

1 HERMAN O. JONES, Primary Examiner 

